Reactions with Group 16 chlorides

The reaction of CCl with CO is reported to result in the formation of considerable quantities of phosgene [1824a], and it is interesting to speculate upon the carbon monoxide behaving as a thermodynamic sink for dichlorine in the well-known and industrially operated reaction [2165]  

The reaction of carbon monoxide with lead(II) chloride is illustrated in Table 5.2 [168]. Thermal decomposition of the lead salt to give dichlorine, followed by reaction with carbon monoxide, could be responsible for the phosgene formation [781]. 

REACTIONS OF CARBON MONOXIDE WITH INORGANIC CHLORIDES 

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On reaction with acyl chlorides and acid anhydrides phenols may undergo either acylation of the hydroxyl group (O acylation) or acylation of the ring (C acylation) The product of C acylation is more stable and predominates under conditions of thermodynamic control when alu mmum chloride is present (see entry 6 m Table 24 4 Section 24 8) O acylation is faster than C acylation and aryl esters are formed under conditions of kinetic control... 

The alcohol groups of carbohydrates undergo chemical reactions typical of hydroxyl functions They are converted to esters by reaction with acyl chlorides and carboxylic acid anhydrides... 

The adamantoate ester is formed selectively from a primary hydroxyl group (e.g., from the 5 -OH in a ribonucleoside) by reaction with adamantoyl chloride, Pyr (20°, 16 h). It is cleaved by alkaline hydrolysis (0.25 N NaOH, 20 min), but is stable to milder alkaline hydrolysis (e.g., NH3, MeOH), conditions that cleave an acetate ester. ... 

The ability to promote /S elimination and the electron-donor capacity of the /3-metalloid substituents can be exploited in a very useful way in synthetic chemistry. Vinylstannanes and vinylsilanes react readily with electrophiles. The resulting intermediates then undergo elimination of the stannyl or silyl substituent, so that the net effect is replacement of the stannyl or silyl group by the electrophile. An example is the replacement of a trimethylsilyl substituent by an acetyl group by reaction with acetyl chloride. 

The chiral acetate reagent is readily prepared from methyl mandelate [methyl (A)-hydroxy-phenyl acetate] which is first converted by treatment with phcnylmagnesium bromide into the triphenylglycol783, c (see Section 1.3.4.2.2.2.) and subsequently transformed into the acetate by reaction with acetyl chloride in the presence of pyridine. Thereby, the secondary hydroxyl group of the glycol is esterified exclusively. Both enantiomers of the reagent are readily accessible since both (R)- and (5)-hydroxyphenylacelic acid (mandelic acids) arc industrial products. 

Although the o-xylylene complex is thermally unstable, it was characterized at — 50 °C by its 1H- and 13C-NMR spectra showing the exocyclic methylene at 5 = 5.04,4.42 ppm (JH) and 5 = 144.8 ppm (13C) using C6D5CD3 as the solvent. Its reaction with benzoyl chloride on the exocyclic carbon leaves a very acidic methylene group which transfers a proton onto the adjacent methylene unit. The double bond is benzoylated again in in situ and a di-cation of the [bis(arene)Fe]2+ type is obtained [47] Scheme VIII. 

As previously discussed, solvents that dissolve cellulose by derivatization may be employed for further functionahzation, e.g., esterification. Thus, cellulose has been dissolved in paraformaldehyde/DMSO and esterified, e.g., by acetic, butyric, and phthalic anhydride, as well as by unsaturated methacrylic and maleic anhydride, in the presence of pyridine, or an acetate catalyst. DS values from 0.2 to 2.0 were obtained, being higher, 2.5 for cellulose acetate. H and NMR spectroscopy have indicated that the hydroxyl group of the methy-lol chains are preferably esterified with the anhydrides. Treatment of celliflose with this solvent system, at 90 °C, with methylene diacetate or ethylene diacetate, in the presence of potassium acetate, led to cellulose acetate with a DS of 1.5. Interestingly, the reaction with acetyl chloride or activated acid is less convenient DMAc or DMF can be substituted for DMSO [215-219]. In another set of experiments, polymer with high o -celliflose content was esterified with trimethylacetic anhydride, 1,2,4-benzenetricarboylic anhydride, trimellitic anhydride, phthalic anhydride, and a pyridine catalyst. The esters were isolated after 8h of reaction at 80-100°C, or Ih at room temperature (trimellitic anhydride). These are versatile compounds with interesting elastomeric and thermoplastic properties, and can be cast as films and membranes [220]. 

With phosphorus trichloride, a rather complex reaction results partly in the formation of [PhaP N uPPha PPhCl]+ Cl. The reactivity of the phosphorus(iii) atom is also demonstrated by its ability to desulphurize thiophosphoryl chloride, and its ready reactions with Group VI elements, diborane, and carbon disulphide ... 

These cyclizations normally involve a carbonyl group. The enamine 109 undergoes a reaction with oxalyl chloride to give an intermediate product 110, which is then cyclized upon treatment with HC1 leading to the angular tricyclic compound 111 in excellent yield (Scheme 11) <1995EJM525>. 

PLLA-fr-PCL) multiblock copolymers were prepared from the coupling reaction between the bischloroformates of carboxylated PLLA with diol-terminated PCL in the presence of pyridine [140]. LLA was polymerized with SnOCt2 and 1,6-hexanediol followed by the reaction with succinic anhydride to provide the dicarboxylated PLLA. The carboxyl end groups were subsequently transformed to acid chloride groups by the reaction with thionyl chloride (Scheme 65). As expected, the molecular weight distributions were broad for all samples (1.84 < Mw/Mn < 3.17). 

Ester 324 is hydrolyzed to acid 325 by refluxing in 10% NaOH. In a reaction with thionyl chloride, acid 325 is converted to acid chloride 326, which is isolated as a solid in 96% yield and consecutively converted into amide 327 in 85% yield. Treatment of amide 327 with LDA extracts a proton from the methyl group. The generated anion is trapped by added benzonitrile. Subsequent cyclocondensation of the obtained imine anion with the amide group provides derivative 328 in 62% isolated yield (Scheme 50) <2003EJM983>. 

Many pyridine-indole compounds are biologically active. A growing number of methods for the preparation of indolylstannanes have been developed. 2-Trialkylstannylindoles, for example, have been synthesized via directed metalation followed by reaction with tin chloride [91-93]. The latest indolylstannane syntheses include Fukuyama s free radical approach to 2-trialkylstannylindoles from novel isonitrile-alkenes [94], and its extension to an isonitrile-alkyne cascade [95]. Assisted by the chelating effect of the SEM group oxygen atom, direct metalation of 1-SEM-indole and transmetalation with BujSnCl afforded 2-(tributylstannyl)-l//-indole 108, which was then coupled with 2,6-dibromopyridine to give adduct 109. 

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